Some very old gits do not support this; it was added in 2.13.0 (2017).
We already sort of detect broken submodules in the configure script,
so this should be safe to remove. Unless the user deliberately
corrupts their repository, there's no difference.
SERNO_FILE="serno.h"
-REVH_NEW="$(git describe --abbrev=20 --always --broken --dirty --long --tags)"
+REVH_NEW="$(git describe --abbrev=20 --always --dirty --long --tags)"
if [ "x${REVH_NEW}" = "x" ]
then